Tolvaptan is an effective treatment for hyponatremia. However, cirrhotic patients were underrepresented in previous studies. The pattern of use and efficacy of tolvaptan in real-life clinical practice are currently unknown.The objective of this study is to evaluate the efficacy of tolvaptan in cirrhotic patients with hyponatremia. The secondary objective is to evaluate the short- to intermediate-term safety of tolvaptan in cirrhotic patients.This will be a phase IV, open-label, prospective cohort study for 7 days. Although not mandatory, study subjects are encouraged to undergo follow-up assessments at 1 month.Subjects will be evaluated at designated time points after initiation of therapy. The primary efficacy endpoint is the proportion of subjects with normal serum sodium level (135-145 mmol/l) on day 7. The secondary efficacy endpoints are serum sodium level, change in sodium level from baseline, quality of life (EQ-5D-3L), change in body weight, edema, renal function, mortality and liver-related complications on day 7 and day 30.